PTE 732: electrical modalities

basic principles of electricity,

what are some examples of contraindications for using electricity with treatment?

• patients with cardiac pacemakers, implantable defibrillator, or unstable arrhythmia

• patients with venous or arterial thrombosis or thrombophlebitis in treatment area

• pregnant patients

using e-stim with pregnant patients is usually frowned upon, but what is one exceptional circumstance?

can use e-stim from pain relief during labor and delivery

what is one area where e-stim/electrodes should never be placed?

over the carotid sinus

list some examples of precautions when using e-stim.

• cardiac disease

• impaired cognition and sensation

• malignant tumors or any cancer

• areas of skin irritation or open wounds

electrical current

the flow of charged particles

• in the human body or electrolytic solutions, it is the flow of ions

electrical charge

matter has wither no net charge (electrically neutral) or is negatively or positively charged

• charge = Q

• charge density= Q/cm²

T or F: a neutral body becomes charged by gaining or losing an electron (e-).

T

what are the three “rules'“ for electric charges?

1. like charges repeal, opposite charges attract

2. charge can be transferred

3. charge cannot be created nor destroyed

ions

elements with either an excess or a deficiency of electrons

• cations: pos

• anions: neg

polarity

indicates relative charge

• anode: pos

• cathode: neg

current

rate of flow of charged particles past a specific point in a specific direction

T or F: positive ions move towards anodes and negative ions move towards cathodes.

F: positive ions → cathodes; negative ions→ anodes

voltage

the force resulting from an accumulation of electrons at one point in an electrical circuit, usually corresponds to a deficit of electrons at another point in the circuit (electrical potential difference)

ampere

unit of measurement that indicates rate of electric current flow

resistance (aka impedance)

opposition to the flow of charged particles

• higher frequency of stimulation = lower resistance/impedance of tissues

what biological tissues are poor conductors of current flow?

• skin

• fat

• bone (poorest)

what biological tissues are good conductors of current flow?

• blood

• muscle

• nerve (best)

conductance

relative ease at which electrons or ions are allowed to move through the conductor

capacitance

property that allows the system to store charge

what are the four circuits of electrical circuits?

1. closed: electrons are flowing

2. open: current flow stops

3. series: only one path

4. parallel: two or more routes exist

direct current (DC)

continuous or uninterrupted uni-directional flow of charged particles > 1 second

• used with iontophoresis, wound healing, and stimulation of denervated muscle

alternating current (AC)

continuous or uninterrupted bi-directional flow of charged particles that must last at least 1 second and must cross the isoelectric line at least twice in 1 second

• used for stimulation of innervated muscle

pulsed current

interruption of either uni- or bi-direcitonal flow of charged particles

T or F: pulsed current is the most commonly used form of electricity in clinical applications and can be used for any stimulation treatment.

F; cannot use with iontophoresis

characteristics of waveforms chart

draw this!

is there a thermal effect with e-stim?

no; cannot measure it

T or F: patients receiving unidirectional flow of DC may experience skin irritation in the form of white dots/blisters.

T

what’s the difference between positive and negative poles? (galvanic effect)

positive poles: the negatively charged particles cause an acidic reaction (Cl-)

negative poles: the positively charged particles cause an alkaline reaction (Na+)

with which current would result in practical elimination of chemical effects at the tissue level?

pulsed current

electrical stimulation may alter the body’s physiology on four levels, what are they?

1. cellular

2. tissue

3. segmental

4. systemic

what magnitude would a patient feel a tingling sensation and muscle contraction?

1-15 mA

what magnitude would a patient feel a painful electrical shock?

15-100 mA

what magnitude would a patient experience a cardiac or respiratory arrest?

100-200 mA

T or F: it takes little intensity (small pulse duration) to stimulate sensory and motor nerves.

T

• sensory is felt first, followed by motor activity

two points are needed for stimulation when testing the nerve conduction velocity. why?

to note time period of the stimulation passing over/through the neuromuslcar junction

how does electrical stimulation modulate pain?

it wither activates the gate control or endogenous opiate mechanisms

“conventional” mode is also called ____ ____.

“high rate”

• generally characterized by a high-rate frequency and low amplitude

some research indicates that frequencies around ___ may be optimal for pain relief.

60 Hz (pps)

describe conventional mode/high rate.

• frequencies in the range of 10-100 pps

• amplitude intensity that produces a comfortable cutaneous stimulation without a contraction

• short pulse duration, usually 50-100 microseconds

describe low rate mode.

• pulse rates (frequencies) below 10, usually 1-4 pps

• pulse duration of 100-300 microseconds

• amplitude adjusted to produce visibly strong and rhythmical muscle contractions

high rate vs low rate chart

when using low rate mode, ____ frequencies tend to work on the gate control mechanism, while ___ frequencies tend to cause endorphin release via the central biasing theory

1. higher

2. lower

to help with neuromuscular dysfunction affecting innervated musculature, what two components must a NMES and FES machine need?

1. ramp up and down time frame

2. time on/off option

can e-stim enhance circulation?

yes!

how does e-stim enhance micro-circulation and protein synthesis thus accelerating the healing process of wounds?

aiding with circulation via motor and sensory stimulation

• muscle contracts = better blood flow (like a pump)

where should a therapist place the 2 electrodes on a patient?

positioned relative to a localized site of painful trauma or inflammation so that stimulation occurs primarily via cutaneous afferents

what are the four electrode placement options (when using 2 electrodes)?

1. just proximal to the site of pain (good for very distal UE or LE sites)

2. just outside the proximal and distal margins of the painful region

3. one on the painful region and the other adjacent to the spine over related spinal root

4. just distal to the site of pain

T or F: specific peripheral nerves that innervate a painful region can be targeted for stimulation, especially where located superficially.

T

• place along nerve pathway

what stimulation may be more effective as the electrodes are placed over motor points since a motor response is a desired outcome when testing peripheral nerves?

“low rate”

can electrodes by placed on trigger points?

they may be positioned relative to the trigger points or relative to its zone of referred pain

• some research suggests that high amplitude stimulation that produces a contraction can aggravate the trigger points

T or F: the current density is directly proportional to the electrode surface area, meaning large impedance= large electrodes.

F; inversely proportional

• larger electrodes = lower impedance (greater current flow)

what are the common uses of electrical stimulation?

• pain control

• muscle re-education and strengthening

• funcitonal electrical stimulation

• edema

• wound healing

list 5 indications for electrical stimulation for pain control.

1. rheumatoid arthritis and osteoarthritis

2. musculoskeletal pain

3. post-surgical pain

4. labor and post-labor pain

5. post-amputation pain

TENS

transcutaneous electrical nerve stimulation

FES

functional electrical stimulation

describe the treatment parameters of Russian stimulation.

• carrier frequency of 2500 Hz

• burst frequency of 50 pps

• intensity to tetanic (sustained) contraction

what are the two qualifications for e-stim to be considered high voltage stimulation (HPVC)?

1. must have twin peak monophasic currents

2. must have 100-150 volts

describe the parameters for high voltage stim (HPVC).

• twin spikes with high amplitude (up to 500V)

• short pulse duration at 50-200 microseconds

• 1-120 pps

does high volt have galvanic effects?

no only iontophoresis!

what are the varied uses for HVPC?

• muscle re-education (requires 150V) to reduce muscle spasm

• nerve stimulation (requires 150V)

• edema reduction and tissue healing

• pain control

T or F: high-voltage stimulation has a high peak, but a low average current provides deep penetration of a comfortable current.

T

HPVC has a physiological response that can be excitatory or non-excitatory. what’s the difference?

excitatory: peripheral nerve stimulation for pain modulation; promotes circulation, inhibits sympathetic nervous system, and endogenous vasodilation

non-excitatory: occurs at a cellular level: protein synthesis, mobilization of blood proteins

what are the precautions for HPVC?

• may cause unwanted tension on muscle fibers

• muscle fatigue if insufficient duty cycle

• improper electrodes can cause burns

• intense stim may result in spasm or soreness

what are the contraindications for HPVC?

• cardiac disability

• pacemakers and metal implants

• pregnancy

• menstruation

• cancerous lesion

• infection

• nerve sensitivity

what is iontophoresis?

a modality that involves the administration of ionic therapeutic agents through the skin by the application of low level electrical current

what kind of current does iontophoresis utilize?

direct current (DC)

iontophoresis is known as an anesthetic (lidocaine), but it is most commonly used to _____ _______, especially when used as a physical therapy modality.

decrease inflammation (dexamethasone)

what are the three methods that iontophoresis works through?

1. heightened transport of charged solutes by electrical repulsion from the electrode

2. enhanced skin permeability due to flow of electrical current

3. altered transport of un-ionized molecules and large polar peptides via electro-osmosis

list a few examples of factors that influence transdermal delivery of iontophoresis.

pH of medication, current density, ionic strength of drug, drug concentration, molecular size, and method of current application (continuous or pulsed)

before starting any electrical stimulation treatment, we should warn the patient that he or she might experience _____ ______.

skin changes!

• like red marks and tiny white bumps

what is the effective dosage for iontophoresis?

40-80 mA x minutes

• 1 mA = 40 mins

• 2 mA = 20 mins

• 4 mA = 10 mins

T or F: transport of drugs across skin is inversely proportional to molecular size, causing smaller peptides to be safer than larger peptides.

T

list some indications for using iontophoresis.

• hyperhidrosis

• plantar fasciitis

• musculoskeletal inflammatory disorders

• rheumatoid disorders

• carpal tunnel syndrome

• scar tissue

what are the contraindications for iontophoresis?

• demand cardiac pacemaker or arrhythmias

• placement of electrodes over carotid sinus

• over venous or arterial thrombosis or thrombophlebitis

• pregnancy

what are the precautions for iontophoresis?

• cardiac disease

• impaired mentation or impaired sensation

• malignant tumor

• skin irritation or open wounds

• after using other physical agents

what are the three main side effects of iontophoresis?

1. erythema

2. itching/burning/tingling

3. minimal blistering

describe the galvanic effects of iontophoresis.

negative electrode = sodium hydroxide = alkaline reaction

positive electrode = hydrochloric acid = acidic reaction

what patient diagnoses can iontophoresis be used for?

• inflammation

• lateral epicondylitis

• hyperhidrosis

• anesthetic

• glucose monitoring

what is biofeedback?

the use of electronic instrumentation to provide objective info (or feedback) to an individual about a physiologic function or response so that the individual becomes aware of his or her response

biofeedback monitors and measures 6 different responses. what are they?

1. EMG

2. EEG

3. blood pressure

4. heart rate

5. temperature

6. any visceral and vasomotor responses

T or F: biofeedback is a tool that clinicians can use to help patients learn new tasks or modify existing motor patterns by providing useful info to the clinician and patient.

T

what three questions are required for the patient to answer before applying and using biofeedback?

1. does the patient have a motor impairment that would suggest that the info provided by biofeedback would be of benefit?

2. do they have the ability for voluntary control?

3. are they motivated and cognitively aware?

why would a therapist use biofeedback?

• muscle re-education

• relaxation of muscle guarding

• pain reduction

• treatment of neurological conditions

what e-stim factors can we manipulate to make a patient’s experience more comfortable?

• intensity

• duration

• frequency

your patient complains she is not feeling anything during e-stim. what are the possibilities for error?

• didn’t properly clean the skin

• cord is frayed or not plugged in

• pulse duration is not long enough

• intensity may not be “high” enough

• frequency is not correctly set

• stimulating at the wrong area

NVC or NCS

nerve conduction velocity

what information is obtained during NVC?

• excitability and fatigability or PNS

• nerve conduction time and velocity

• amplitude and duration of action potential

what are the recording techniques and general considerations when using NCV?

1. securely fasten electrodes to subject with tape or straps

2. clearly mark points of stimulation

3. use metal measuring tape

4. cathode positioned toward active (recording) electrode

5. apply adequate stimulus to evoke a motor or sensory response

what must we subject tract when using NVC?

the time it takes for the stimulus to cross the neuromuscular junction

what are the considerations for patient positioning?

• consider patient’s comfort

• easy accessibility of the extremity for examiner

• positioning of nerve segment

T or F: for all techniques in the NIOSH manual, the cathode (negative pole) of the stimulating electrode is positioned toward the active electrode.

T

compound muscle action potential diagram

motor nerve conduction tests table

T or F: when conducting sensory nerve tests, repeated testing of the same nerve gives no new info.

T

sensory nerve conduction tests table

an antidromic study results in a _____ amplitude sensory nerve action potential (SNAP) whereas an orthodromic study results in a _____ amplitude SNAP.

1. higher

2. smaller

F-Wave

elicited by a supra-maximal stimulus of a peripheral nerve at a distal site; both orthodromic (to distal muscle) and antidromic (to anterior horn cell) responses

• impulse is thought to reverberate

repetitive stimulation

test is designed to test for a neuromuscular transmission disease

• a muscle is repetitively stimulated via tits nerve at a frequency of at least 1/sec in order to deplete the Ach in the neruomuscular junction

what are the sites of involvement of/for electromyography?

• cortex

• tracts

• anterior horn cells

• nerve root

• neuromusclar junciton

• muscle membrane

• muscle fibers